The water in ponds and aquaria tends to become dirty over time due to an accumulation of algae and other debris. Accordingly, water filters are known which include a chamber including filter media. The filter media may comprise open cell foam, sand, beads or other elements some, or all, of which may be substantially inert relative to the water. The water is passed through the filter chamber, and hence the filter media, such that the debris is substantially removed from it.
As an alternative, or in addition, to the use of filters other methods of treating the water are known such as UV lamps and the addition of biological and/or chemical substances, or agents. One way to introduce these substances into the water is by the use of a dosing chamber which is in fluid connection with the water filter, and/or pump. Such doing chambers typically comprise a container into which the dosing substances may be placed. A water inlet and a water outlet are also provided. Accordingly, in use, water enters the container and is dosed before exiting the container. Dosing substances may be in the form of liquids, tablets, granules and gels, however this list is not exhaustive.
In systems where the water is pressurised, either because it is pumped or because the dosing chamber is at a lower level than the source of water (such as a pond), it is necessary to isolate the chamber before opening it to place dosing substances therein. Typically this is achieved by a valve provided in the conduit supplying the water to the water inlet. A valve in the conduit taking the water away from the water outlet may also typically be provided with a valve, especially if the outlet is connected to a source of water (such as a waterfall header tank) which is higher than the dosing chamber.
In domestic ponds, the user must isolate the chamber prior to opening it. If this is not done then when the lid is removed, or the chamber opened in some other way, water may gush from the chamber under pressure possibly causing injury.
Accordingly, it is desirable to have a dosing chamber wherein the act of removing the lid isolates at least the water inlet such that when the lid is removed no pressurised water escapes from the chamber.